The objective of this application is to illustrate the core constituents of the ocular surface microbiome, describe factors that promote colonization, and assess the ocular microbiome's role in the health of the anterior segment. We will conduct a prospective, observational cohort study, including a longitudinal analysis of the ocular microbiome in adults.

The microbiome is defined as a community of microbial organisms that reside in a specific host niche. There is a growing body of literature on the association between gut microbiome and disease entities such as inflammatory bowel disease, colon cancer and presumably an association that might influence response to treatment in some patients.

Recent data suggest the existence of a resident ocular microbiota that may play a protective role in corneal infections [1-4]. However, not much is known about the ocular microbiome and its association with disease or response to treatment. The National Eye Institute (NEI) recently hosted a symposium to discuss challenges to characterize the ocular microbiome and its role in promoting or preventing ocular diseases. One of the major challenges discussed is the lack of a normative population- based database describing the ocular microbiome.

In response the NEI as part of the Anterior segment initiative put out an RFA requesting proposals on methods of collection of biological samples and associated clinical data (e.g. demographic, residence, medications, allergies); processing of samples to extract analytes (e.g., DNA, RNA, protein, metabolites) and characterizing microorganisms in a low biomass niche, specifically the ocular surface using16S rRNA marker gene, whole metagenome sequencing (WMS), and metatranscriptomics approaches.

Inclusion Criteria:

We will include subjects who meet all of the following criteria:

• 18 years of age or older
• Provide informed consent
• Cohort A - normal eyes with no ocular disease
• Cohort B - primary open angle glaucoma/Ocular hypertension defined as mild glaucoma which is well controlled with no more than one drop of prostaglandin use daily for the past 6 months
• Cohort C - non-infectious keratopathy not using any prescription medication (OTC artificial tears are acceptable)
• Cohort D - Dry AMD (age related macular degeneration)
• Cohort E - Wet AMD
• Cohort F - diabetic retinopathy

Exclusion Criteria:

We will exclude subjects who meet all of the following criteria:

• Prior ocular disease either of the anterior or posterior segment
• Any medical comorbidities except well controlled DH and HTN
• Unable to follow up with study procedures as described

We anticipate there will be approximately 20% failure rate due to the low bacterial load in these samples and so we will have to collect more samples to account for the loss of data.

We estimate that 20 patients in each cohort of eyes with ocular disease - 100 total patients and 500 normal eyes will give us sufficient power to explore this topic.